If length is the problem, it may not be worth worrying about. I haven't looked at the sizes since I ordered Boone's, but they vary quite a bit for different shapes. I went with a size 20 for Boone. With a long Catahoula body, none of them would have actually made it all the way down to his tail. That one was just closest to his chest and neck size. I'm really pleased with how it fits him, though.